Village Loudspeakers

[mystwoodcol]

Lucky you don't live down South near a mosque . They star at 5am and will wake the dead no matter what you do. I once live in a high rise surrounded by mosques 6 in fact and they all had their loud speakers aimed at the high rise that was full of farangs. 6 out of sync. Think yourself lucky with the village speakers

[Lite Beer]

I was sitting here all day with no electric which means no water for showers or flushing the toilet

litebeer, thailand the land of large garbage pails filled with water and a plastic bowl for both shower and toilet convenience... i indeed appreciate the training i received in thailand with both bowl and bucket, when we have water/electric issues here (happens often enough)...

bina

israel

Yep. Thats what most of the villagers do. A bit cold in the winter throwing a bucket of water over yourself.

If I know in advance I fill up a few buckets. The water containers are empty because it has not rained for months.

[ProThaiExpat]

In line with the 5k baht donation suggestion, I would try a conference with the village chief offering to pay an electrician of the kaman's choice to relocate the speaker and point it in another direction once relocated. Allowing the kaman to choose the electrician allows for enough "grease" to be structured into the deal to be appealing and that way the kaman stays in control and he doesn't loose face.

My ten years of experience and from what my Thai partner tells me, many Thais are just not into complaining and those receiving complaints don't honestly know how to handle them.

However, sound is unpredictable and our local speaker. in an otherwise very quiet neighborhood, could be relocated but I have no confidence that the sound would not travel to my ears as before.

[colinscarr]

We have the same problem, with a LOUDspeaker just across the road from us.

However, last month things were a bit different...

One morning they announced a free handout of duvets for old folks to keep warm at night, so Grandma was delighted.

Next morning they announced something, and the wife leapt out of bed & jumped on her motorbike. It seems they were giving away bags of fertiliser & since we've just bought a farming plot this was excellent news.

I'd still be tempted by the wirecutters option though...

[bartender100]

I remember reading once about putting a small nail or pin though the cable of the speaker disables it, and hard to spot, not sure if it works.

BTW wax earplugs can be brought in most pharmacies about B90, but they are only good for a few users, as they lose their stickiness, but they are comfortable and block out everything

[a99az]

Active Noise Cancellation

by Ron Kurtus (revised 21 February 2007)

Noise cancellation is a method to reduce or completely cancel out undesirable sound, such that you can't hear it. It is often call Active Noise Cancellationbecause the electronics involved actively cause the noise cancellation in real time.

In the case of a single sound frequency, you can add the same frequency 180° out of phase to cancel the sound. It is much more difficult with complex sounds, such as the spoken word. The most common electronic noise cancellation device consists of special earphones. Other types of devices that do not require earphones are being developed. Note that this is an emerging technology and is often not available for common noise problems.

Questions you may have about such a device are:

• How can you cancel out simple waveforms?
• How is complex sound cancelled out?
• What are some noise cancellation applications?

This lesson will answer these questions. There is a mini-quiz near the end of the lesson.

Useful tools: Metric-English Conversion | Scientific Calculator.

Simple wave cancellation

Although sound is a compression wave, each tone or frequency can be represented by a sine wave of a given wavelength.

Simple sine wave for single sound frequency

Slightly out of phase

Suppose another pure sound of the same frequency was emitted, but just a fraction of a second later. That means it is slightly out of phase from the first sound or sine wave. The visual representation of the two waves would be as in the next illustration.

One pure sound a fraction of a second after the next

Graphing the result

You can graphically see what the resulting wave would look like by adding values above and below the centerline (zero). This is illustrated by the green dots in the following drawing. The green line is approximately a sine wave of the same frequency.

Sum of two waves slightly out of phase

You would hear the same frequency, except that the sound would be twice as loud as the original. Note that since the frequencies are the same, you would not hear beat sounds.

(See Beat Frequencies in Sound for more information on that subject.)

Sound cancellation

Finally, if the sound waves were 180° or one-half a wavelength out of phase, the sum of the waveforms would be zero. They would cancel out each other and there would be no sound.

Sum of waves equals zero sound

How is it possible in air?

Although it is difficult to accept that adding two sounds can result in zero sound, you need to remember that sound is a compression wave in air or other media. That means the wave first compresses to an amount greater than normal air pressure. This is the positive part of the sine wave graphic. Then the air expands to a pressure less than normal air pressure. This is the negative part of the sine wave—the part below the zero centerline. Adding the positive pressure and negative pressure will give you the normal air pressure.

Canceling complex waves

Electronically, it would be simple to detect a simple tone, adjust it 180° out of phase and add it to the original, thus canceling out the sound. Unfortunately, most sound is much more complex than a simple sine wave.

Complex waveform of a spoken word

Spectrum of frequencies

A spoken word consists of a spectrum of frequencies of different amplitudes. This means that to cancel out each waveform, the electronics would need to filter each frequency separately, determine its frequency, create the same frequency and amplitude at 180° out of phase, and then add it to the original.

Not perfect

Since there are so many frequencies and fractions of frequencies in some sounds, it is impossible to cancel them all out with this method. Instead, the electronics selects a narrow band of frequencies and averages out the result. This is a fairly good job at noise cancellation, but it is not 100%.

Applications

There are a number of great applications for active noise cancellation devices.

Noise cancellation almost requires the sound to be cancelled at a source, such as from a loud speaker. That is why the effect works well with headsets, since you can contain the original sound and the canceling sound in an area near your ear. In applications where the sound comes from many areas, such as in a room, it is difficult to cancel the sound from each area. But, scientists and engineers are working on solutions.

Headsets

One obvious application is that people working near aircraft or in noisy factories can now wear these electronic noise cancellation headsets to protect their hearing.

Students can wear these headsets to cancel out unwanted noise, while being able to listen to their own music while they study. These headsets are now fairly inexpensive, costing around $50.

Honda cars

Honda is now using noise-cancellation technology in their Japan-only Accord station wagon.

The way it works is that a microphone connected to the car stereo system picks up all the sound inside the car, including music or such from the stereo. Then the noise-cancellation system subtracts the sound of the music coming from the stereo and produces noise-canceling sound waves that match the frequency of unwanted sound.

The noise-canceling sound waves are also sent through the stereo speakers, along with the music. This technique greatly reduces the low frequency vibration noises in the car, without dampening the car's audio system.

Unfortunately, Honda is not shipping the noise-cancellation system outside Japan.

Space satellite antennas

Some space satellites have long antennas. If such an antenna would start to vibrate wildly, it could throw the satellite out of orbit and out of control. By detecting the waveform or any vibration in the antenna, it can be suppressed in the same way that noise is suppressed.

A piezoelectric device creates an electrical signal when it detects a vibration. It also will vibrate according to an electrical signal it receives. Putting piezoelectric devices on the antenna can result in vibrating the antenna in an opposite phase, thus eliminating the dangerous motion.

Use in apartments

One cool idea is to suppress unwanted noise from another apartment by vibrating your wall out of phase with the sound from next door.

For example, suppose the person in the next apartment has his stereo on real loud. In some cases, you can even feel the wall vibrate. By placing devices on the wall, you can detect the wall vibrations and generate vibrations in an opposite phase. Thus would completely cancel out the noise coming from the other apartment.

Although there are some new devices available that use your walls as a speaker by creating vibrations, it has not yet been combined with detectors and noise reduction electronics. This is an invention that is begging to be developed.

Summary

Active noise cancellation is a method to cancel out undesirable sound in real time. It is relatively easy to do with a single sound frequency, but it is much more difficult with complex sounds, such as the spoken word. Noise cancellation earphones are the most common devices. Other devices that do not require earphones are being developed.

[PingManDan]

Over in Cha-Am - Hua Hin area the Muslims start with their prayers at around 4:30 to 5:30 am your lucky

[tim armstrong]

I don't want to destroy any property as that could land me in hot water. One thing I'd considered was placing a hood of some kind over the speaker, directing the sound upward.

I'm gratified to learn from Bobbin's post that a small number of people petitioning can get something done. Failing that, a small ANC device would be fine -- I'll see if I can pick one up in Akihabara.

I don't want to destroy anything and I certainly have no need to defeat anybody. I just want to get what I want.

Now turning the speaker upwards enough to capture any passing rain drops might be worth a try??

[Latindancer]

I think that destroying the speakers or stopping the sound completely will bring too swift a fixing-up by the authorities.

So Travelmann's response is probably the best.....put a resistor inline .....or better, your own volume control. However as I see you don't want to get caught doing anything like that, probably the best is to slightly disable it.

Remember you are living in Asia. It is full of half-working things that never get fixed. Pour some liquid inside it. Or spray something into it. What about an aerosol can of polystyrene (expanding foam ) ?

Just put in enough to make the sound much softer, but the foam can't really be seen. Then, if you want to silence it totally, gradually help the speaker to "die", bit by bit........all in the dead of the night, of course.

Mind you, the FM radio idea is excellent, too ! I thought of this in relation to Bangkok taxis, and may actually do it. I have to tweak a little knob out of sight of the driver in order to tune in to the station he is listening to, but that's easy. I hate the kind of music that's on a lot of the time. I'll do it twice, but if the driver changes station twice, I'll stop before he cottons on.......

I'll play music from my own player on his radio ! Brilliant !

Edited February 3, 2011 by Latindancer

[JimsKnight]

Wire cutters in the middle of the nite should solve the problem

+1

[tim armstrong]

We've had some progress on our speaker problem. My wife and I and a small delegation of her friends went to see the local chief admin. guy today. I sat in the back of the room while the rest talked forcefully and continuously over the top of each other for about 30 mins.

Outcome:

1. The guy who had been given the brief to broadcast info to the local farmers at 5am had overstepped the mark, by broadcasting very loud music to his mates, and no info much at all.

2. The administrator has already warned him to change his ways (yeah, yeah?)

3. If he doesn't change by this Monday am he will not be allowed to broadcast anymore, and the equipment given to someone else who will lower the volume and conform to the 'local regulations'(yeah, yeah)

4. If he doesn't stop and refuses to give up the equipment, the police will become involved. So roll on Monday.

Lesson learnt -I hope - a small group of angry Thai women can achieve a lot when pushed !! I will keep you posted.

[Dutchie01]

Get a needle and cut it at a length just so it is as long as the speaker wire is wide.

Get some pliers and push the needle through the wire. a short they wont find that easily

Dutchie01

[jimbeam1]

Every morning from 7 to 8 and again in the evening from 5:25 to 6:00

Just think yourself lucky that it is not 5.30 or 6-00 am as it is where I live.

As said you ain't gonna stop it. It's the Phuyai doing his job.

Same as you Lite Beer, 5.30 - 6.00 in the morning. Also an issue with the bloody Cockerels, I think they woke the Phuyai. My solution I moved out. Still miss the house sometimes though.

jb1

Edited February 5, 2011 by jimbeam1

[BlackJack]

i think speakers and wires corrode when outside

and some exposure to chemicals speed up the process

looks natural

nudge nudge wink wink

[exbelg]

if you live near moslim mosque, good luck ... i had the bad luck of for about a year than moved as it drove me crazy each morning at 5 am...

[haybilly]

if you live near moslim mosque, good luck ... i had the bad luck of for about a year than moved as it drove me crazy each morning at 5 am...

Agreed, when living in South Thailand the 'call to prayer' at start of day was very trying--however, having read the vast majority of comments on this Topic I am forced to write that--You, and I, are the guests in this country and, although there are countless things that will probably annoy our Western sensibilities--it's got very little, or even FA, to do with us--so, put up with their customs, habits and annoyances or relocate.

I hope that I don't sound too unsympathetic but I fear that this the truth.

[Iamemjay]

We have a speaker right outside our house. I found it educative that on two occasions it has gone out of action (reason??) and it took many months for them to get around to fixing it. Our neighbours were not concerned as they could still hear enough of the ones further up the street to not miss out on eg, when the electricity bill had to be paid, but was quiet enough to be entirely tolerable.

I therefore think one of the disabling techniques mentioned above should be employed.

When remodeling our bedroom we fully insulated it (walls ceiling), so even when the pesky thing works and starts at 6.30am - the usual starting time - it now doesn't bother us at all if still in bed - and the bedroom is cooler/warmer when required!

[philhal2]

I don't want to destroy any property as that could land me in hot water. One thing I'd considered was placing a hood of some kind over the speaker, directing the sound upward.

I'm gratified to learn from Bobbin's post that a small number of people petitioning can get something done. Failing that, a small ANC device would be fine -- I'll see if I can pick one up in Akihabara.

I don't want to destroy anything and I certainly have no need to defeat anybody. I just want to get what I want.

Good luck.

Maybe acceptance of what is in place where you choose to live ? , along with the ear plugs ? Perhaps maybe you might need to return to your place of origon to avoid the complications of dealing with the local way of life ?

[philhal2]

Active Noise Cancellation

by Ron Kurtus (revised 21 February 2007)

Noise cancellation is a method to reduce or completely cancel out undesirable sound, such that you can't hear it. It is often call Active Noise Cancellationbecause the electronics involved actively cause the noise cancellation in real time.

In the case of a single sound frequency, you can add the same frequency 180° out of phase to cancel the sound. It is much more difficult with complex sounds, such as the spoken word. The most common electronic noise cancellation device consists of special earphones. Other types of devices that do not require earphones are being developed. Note that this is an emerging technology and is often not available for common noise problems.

Questions you may have about such a device are:

• How can you cancel out simple waveforms?
• How is complex sound cancelled out?
• What are some noise cancellation applications?

This lesson will answer these questions. There is a mini-quiz near the end of the lesson.

Useful tools: Metric-English Conversion | Scientific Calculator.

Simple wave cancellation

Although sound is a compression wave, each tone or frequency can be represented by a sine wave of a given wavelength.

Simple sine wave for single sound frequency

Slightly out of phase

Suppose another pure sound of the same frequency was emitted, but just a fraction of a second later. That means it is slightly out of phase from the first sound or sine wave. The visual representation of the two waves would be as in the next illustration.

One pure sound a fraction of a second after the next

Graphing the result

You can graphically see what the resulting wave would look like by adding values above and below the centerline (zero). This is illustrated by the green dots in the following drawing. The green line is approximately a sine wave of the same frequency.

Sum of two waves slightly out of phase

You would hear the same frequency, except that the sound would be twice as loud as the original. Note that since the frequencies are the same, you would not hear beat sounds.

(See Beat Frequencies in Sound for more information on that subject.)

Sound cancellation

Finally, if the sound waves were 180° or one-half a wavelength out of phase, the sum of the waveforms would be zero. They would cancel out each other and there would be no sound.

Sum of waves equals zero sound

How is it possible in air?

Although it is difficult to accept that adding two sounds can result in zero sound, you need to remember that sound is a compression wave in air or other media. That means the wave first compresses to an amount greater than normal air pressure. This is the positive part of the sine wave graphic. Then the air expands to a pressure less than normal air pressure. This is the negative part of the sine wave—the part below the zero centerline. Adding the positive pressure and negative pressure will give you the normal air pressure.

Canceling complex waves

Electronically, it would be simple to detect a simple tone, adjust it 180° out of phase and add it to the original, thus canceling out the sound. Unfortunately, most sound is much more complex than a simple sine wave.

Complex waveform of a spoken word

Spectrum of frequencies

A spoken word consists of a spectrum of frequencies of different amplitudes. This means that to cancel out each waveform, the electronics would need to filter each frequency separately, determine its frequency, create the same frequency and amplitude at 180° out of phase, and then add it to the original.

Not perfect

Since there are so many frequencies and fractions of frequencies in some sounds, it is impossible to cancel them all out with this method. Instead, the electronics selects a narrow band of frequencies and averages out the result. This is a fairly good job at noise cancellation, but it is not 100%.

Applications

There are a number of great applications for active noise cancellation devices.

Noise cancellation almost requires the sound to be cancelled at a source, such as from a loud speaker. That is why the effect works well with headsets, since you can contain the original sound and the canceling sound in an area near your ear. In applications where the sound comes from many areas, such as in a room, it is difficult to cancel the sound from each area. But, scientists and engineers are working on solutions.

Headsets

One obvious application is that people working near aircraft or in noisy factories can now wear these electronic noise cancellation headsets to protect their hearing.

Students can wear these headsets to cancel out unwanted noise, while being able to listen to their own music while they study. These headsets are now fairly inexpensive, costing around $50.

Honda cars

Honda is now using noise-cancellation technology in their Japan-only Accord station wagon.

The way it works is that a microphone connected to the car stereo system picks up all the sound inside the car, including music or such from the stereo. Then the noise-cancellation system subtracts the sound of the music coming from the stereo and produces noise-canceling sound waves that match the frequency of unwanted sound.

The noise-canceling sound waves are also sent through the stereo speakers, along with the music. This technique greatly reduces the low frequency vibration noises in the car, without dampening the car's audio system.

Unfortunately, Honda is not shipping the noise-cancellation system outside Japan.

Space satellite antennas

Some space satellites have long antennas. If such an antenna would start to vibrate wildly, it could throw the satellite out of orbit and out of control. By detecting the waveform or any vibration in the antenna, it can be suppressed in the same way that noise is suppressed.

A piezoelectric device creates an electrical signal when it detects a vibration. It also will vibrate according to an electrical signal it receives. Putting piezoelectric devices on the antenna can result in vibrating the antenna in an opposite phase, thus eliminating the dangerous motion.

Use in apartments

One cool idea is to suppress unwanted noise from another apartment by vibrating your wall out of phase with the sound from next door.

For example, suppose the person in the next apartment has his stereo on real loud. In some cases, you can even feel the wall vibrate. By placing devices on the wall, you can detect the wall vibrations and generate vibrations in an opposite phase. Thus would completely cancel out the noise coming from the other apartment.

Although there are some new devices available that use your walls as a speaker by creating vibrations, it has not yet been combined with detectors and noise reduction electronics. This is an invention that is begging to be developed.

Summary

Active noise cancellation is a method to cancel out undesirable sound in real time. It is relatively easy to do with a single sound frequency, but it is much more difficult with complex sounds, such as the spoken word. Noise cancellation earphones are the most common devices. Other devices that do not require earphones are being developed.

SUMMARISING THIS , WHAT A LOAD OF WANK JUICE

[craig]

I moved into a rural district south of Pattaya five years ago...Same problem...loudspeakers blaring away in the am and pm..then it toned way down. I asked my wife what happened. It seems a block of homes in the other direction complained...they must have been influential Thais as it did the trick. Indeed, in a fit of pique, the local headman complained that if these folks complained he wouldn't let them hear it at all and removed the speaker facing that direction. We still get it, not every morning and much quieter..I just go inside & turn up the TV.

Now if I could only resolve the bass thumping sounds whenever someone feels the need to throw a party and make sure everyone in the hemisphere knows they have a big pair of speakers.

Nothing for it but to do as has been suggested...grin& bear it or leave.

Don't even think about cutting wires or such..if you do it in your pale skin you will be seen by someone and will take it up the ass...

[TheGhostWithin]

Guys, guys.. we are visitors, or at best long-term residents who call Thailand Home (not me personally, but many of you are). When you lived in your home countries, did it not irritate you when foreigners came to your countries, bringing in their customs, their attitudes to your way of life? it is an ongoing issue where I live.

Would stopping the village speaker, which is something ingrained in these outer villages, not be interferring with their culture? Being the only Farang there, you have adopted the Thai way of life at least to some degree. I

Cutting the wires, considering your wife is from the village and you live there, may have implications for the family, and be seen as a rejection of the authority of the Phuu Yai - I would strongly advise avoiding this course of action if at all possible. To a degree, it may even be seen by some as the village Farang rejecting the village way of life, and a loss of face for the family to allow this behaviour. If you HAVE to go down this route, have your wife pay someone else, who pays someone else to do the job. Make sure it does not lead back to you, or to the family. Money can make you anonymous in Thailand, like a big invisible cloak or a shining red shirt.

n Thai Culture, giving money to the Phuu Yai is considered a "donation", in exchange for him moving the speaker, or at least turning that particular speaker down to a level you agree is acceptable. At hope, this would border on bribery but this is Thailand - when in Thailand, do as the Thais do.

I actually found it very interesting, the whole speaker thing in my Girlfriends Village, but can see the annoying side to it.

[cigar7]

If you cut the wire they will eventually repair it.

Push a small pin through the cable, so that it shorts the 2 conductors - preferably in a buried location. Snip off the protruding ends so that it will be difficult to locate the fault. This will keep then busy trying to rectify the problem and they likely will either give up, or decide that there is no budget to replace defective electronics.

Do not do this when the wire is live.

Have fun

Good suggestions The 'no budget' angle is a good one. Some of the speakers have disappeared in our area. Definitely no money to replace them. Unusually my wife and SIL marched off with some friends recently to complain to the local admin. But no change yet. Its a pity some rats couldn't be trained as they love plastic insulation. I had a dream about this event, but I couldn't work out which wire to cut, and I got fried and fell off the ladder. (Too many movies) Sorry, I don't have a solution, maybe the earplugs

This is a great idea! You may choose to do this in a couple of places along the cable. The cable may also be running inside the pole up to the loud speakers. The pole will probably have an access panel near the base, which can be opened to access the cables.

[HeavyDrinker]

We don't have them. Too posh here.

[Tanaka]

Active Noise Cancellation

by Ron Kurtus (revised 21 February 2007)

Noise cancellation is a method to reduce or completely cancel out undesirable sound, such that you can't hear it. It is often call Active Noise Cancellationbecause the electronics involved actively cause the noise cancellation in real time.

In the case of a single sound frequency, you can add the same frequency 180° out of phase to cancel the sound. It is much more difficult with complex sounds, such as the spoken word. The most common electronic noise cancellation device consists of special earphones. Other types of devices that do not require earphones are being developed. Note that this is an emerging technology and is often not available for common noise problems.

Questions you may have about such a device are:

• How can you cancel out simple waveforms?
• How is complex sound cancelled out?
• What are some noise cancellation applications?

This lesson will answer these questions. There is a mini-quiz near the end of the lesson.

Useful tools: Metric-English Conversion | Scientific Calculator.

Simple wave cancellation

Although sound is a compression wave, each tone or frequency can be represented by a sine wave of a given wavelength.

Simple sine wave for single sound frequency

Slightly out of phase

Suppose another pure sound of the same frequency was emitted, but just a fraction of a second later. That means it is slightly out of phase from the first sound or sine wave. The visual representation of the two waves would be as in the next illustration.

One pure sound a fraction of a second after the next

Graphing the result

You can graphically see what the resulting wave would look like by adding values above and below the centerline (zero). This is illustrated by the green dots in the following drawing. The green line is approximately a sine wave of the same frequency.

Sum of two waves slightly out of phase

You would hear the same frequency, except that the sound would be twice as loud as the original. Note that since the frequencies are the same, you would not hear beat sounds.

(See Beat Frequencies in Sound for more information on that subject.)

Sound cancellation

Finally, if the sound waves were 180° or one-half a wavelength out of phase, the sum of the waveforms would be zero. They would cancel out each other and there would be no sound.

Sum of waves equals zero sound

How is it possible in air?

Although it is difficult to accept that adding two sounds can result in zero sound, you need to remember that sound is a compression wave in air or other media. That means the wave first compresses to an amount greater than normal air pressure. This is the positive part of the sine wave graphic. Then the air expands to a pressure less than normal air pressure. This is the negative part of the sine wave—the part below the zero centerline. Adding the positive pressure and negative pressure will give you the normal air pressure.

Canceling complex waves

Electronically, it would be simple to detect a simple tone, adjust it 180° out of phase and add it to the original, thus canceling out the sound. Unfortunately, most sound is much more complex than a simple sine wave.

Complex waveform of a spoken word

Spectrum of frequencies

A spoken word consists of a spectrum of frequencies of different amplitudes. This means that to cancel out each waveform, the electronics would need to filter each frequency separately, determine its frequency, create the same frequency and amplitude at 180° out of phase, and then add it to the original.

Not perfect

Since there are so many frequencies and fractions of frequencies in some sounds, it is impossible to cancel them all out with this method. Instead, the electronics selects a narrow band of frequencies and averages out the result. This is a fairly good job at noise cancellation, but it is not 100%.

Applications

There are a number of great applications for active noise cancellation devices.

Noise cancellation almost requires the sound to be cancelled at a source, such as from a loud speaker. That is why the effect works well with headsets, since you can contain the original sound and the canceling sound in an area near your ear. In applications where the sound comes from many areas, such as in a room, it is difficult to cancel the sound from each area. But, scientists and engineers are working on solutions.

Headsets

One obvious application is that people working near aircraft or in noisy factories can now wear these electronic noise cancellation headsets to protect their hearing.

Students can wear these headsets to cancel out unwanted noise, while being able to listen to their own music while they study. These headsets are now fairly inexpensive, costing around $50.

Honda cars

Honda is now using noise-cancellation technology in their Japan-only Accord station wagon.

The way it works is that a microphone connected to the car stereo system picks up all the sound inside the car, including music or such from the stereo. Then the noise-cancellation system subtracts the sound of the music coming from the stereo and produces noise-canceling sound waves that match the frequency of unwanted sound.

The noise-canceling sound waves are also sent through the stereo speakers, along with the music. This technique greatly reduces the low frequency vibration noises in the car, without dampening the car's audio system.

Unfortunately, Honda is not shipping the noise-cancellation system outside Japan.

Space satellite antennas

Some space satellites have long antennas. If such an antenna would start to vibrate wildly, it could throw the satellite out of orbit and out of control. By detecting the waveform or any vibration in the antenna, it can be suppressed in the same way that noise is suppressed.

A piezoelectric device creates an electrical signal when it detects a vibration. It also will vibrate according to an electrical signal it receives. Putting piezoelectric devices on the antenna can result in vibrating the antenna in an opposite phase, thus eliminating the dangerous motion.

Use in apartments

One cool idea is to suppress unwanted noise from another apartment by vibrating your wall out of phase with the sound from next door.

For example, suppose the person in the next apartment has his stereo on real loud. In some cases, you can even feel the wall vibrate. By placing devices on the wall, you can detect the wall vibrations and generate vibrations in an opposite phase. Thus would completely cancel out the noise coming from the other apartment.

Although there are some new devices available that use your walls as a speaker by creating vibrations, it has not yet been combined with detectors and noise reduction electronics. This is an invention that is begging to be developed.

Summary

Active noise cancellation is a method to cancel out undesirable sound in real time. It is relatively easy to do with a single sound frequency, but it is much more difficult with complex sounds, such as the spoken word. Noise cancellation earphones are the most common devices. Other devices that do not require earphones are being developed.

SUMMARISING THIS , WHAT A LOAD OF WANK JUICE

Just because you could not understand any of it!

[mystwoodcol]

Active Noise Cancellation

by Ron Kurtus (revised 21 February 2007)

Noise cancellation is a method to reduce or completely cancel out undesirable sound, such that you can't hear it. It is often call Active Noise Cancellationbecause the electronics involved actively cause the noise cancellation in real time.

In the case of a single sound frequency, you can add the same frequency 180° out of phase to cancel the sound. It is much more difficult with complex sounds, such as the spoken word. The most common electronic noise cancellation device consists of special earphones. Other types of devices that do not require earphones are being developed. Note that this is an emerging technology and is often not available for common noise problems.

Questions you may have about such a device are:

• How can you cancel out simple waveforms?
• How is complex sound cancelled out?
• What are some noise cancellation applications?

This lesson will answer these questions. There is a mini-quiz near the end of the lesson.

Useful tools: Metric-English Conversion | Scientific Calculator.

Simple wave cancellation

Although sound is a compression wave, each tone or frequency can be represented by a sine wave of a given wavelength.

Simple sine wave for single sound frequency

Slightly out of phase

Suppose another pure sound of the same frequency was emitted, but just a fraction of a second later. That means it is slightly out of phase from the first sound or sine wave. The visual representation of the two waves would be as in the next illustration.

One pure sound a fraction of a second after the next

Graphing the result

You can graphically see what the resulting wave would look like by adding values above and below the centerline (zero). This is illustrated by the green dots in the following drawing. The green line is approximately a sine wave of the same frequency.

Sum of two waves slightly out of phase

You would hear the same frequency, except that the sound would be twice as loud as the original. Note that since the frequencies are the same, you would not hear beat sounds.

(See Beat Frequencies in Sound for more information on that subject.)

Sound cancellation

Finally, if the sound waves were 180° or one-half a wavelength out of phase, the sum of the waveforms would be zero. They would cancel out each other and there would be no sound.

Sum of waves equals zero sound

How is it possible in air?

Although it is difficult to accept that adding two sounds can result in zero sound, you need to remember that sound is a compression wave in air or other media. That means the wave first compresses to an amount greater than normal air pressure. This is the positive part of the sine wave graphic. Then the air expands to a pressure less than normal air pressure. This is the negative part of the sine wave—the part below the zero centerline. Adding the positive pressure and negative pressure will give you the normal air pressure.

Canceling complex waves

Electronically, it would be simple to detect a simple tone, adjust it 180° out of phase and add it to the original, thus canceling out the sound. Unfortunately, most sound is much more complex than a simple sine wave.

Complex waveform of a spoken word

Spectrum of frequencies

A spoken word consists of a spectrum of frequencies of different amplitudes. This means that to cancel out each waveform, the electronics would need to filter each frequency separately, determine its frequency, create the same frequency and amplitude at 180° out of phase, and then add it to the original.

Not perfect

Since there are so many frequencies and fractions of frequencies in some sounds, it is impossible to cancel them all out with this method. Instead, the electronics selects a narrow band of frequencies and averages out the result. This is a fairly good job at noise cancellation, but it is not 100%.

Applications

There are a number of great applications for active noise cancellation devices.

Noise cancellation almost requires the sound to be cancelled at a source, such as from a loud speaker. That is why the effect works well with headsets, since you can contain the original sound and the canceling sound in an area near your ear. In applications where the sound comes from many areas, such as in a room, it is difficult to cancel the sound from each area. But, scientists and engineers are working on solutions.

Headsets

One obvious application is that people working near aircraft or in noisy factories can now wear these electronic noise cancellation headsets to protect their hearing.

Students can wear these headsets to cancel out unwanted noise, while being able to listen to their own music while they study. These headsets are now fairly inexpensive, costing around $50.

Honda cars

Honda is now using noise-cancellation technology in their Japan-only Accord station wagon.

The way it works is that a microphone connected to the car stereo system picks up all the sound inside the car, including music or such from the stereo. Then the noise-cancellation system subtracts the sound of the music coming from the stereo and produces noise-canceling sound waves that match the frequency of unwanted sound.

The noise-canceling sound waves are also sent through the stereo speakers, along with the music. This technique greatly reduces the low frequency vibration noises in the car, without dampening the car's audio system.

Unfortunately, Honda is not shipping the noise-cancellation system outside Japan.

Space satellite antennas

Some space satellites have long antennas. If such an antenna would start to vibrate wildly, it could throw the satellite out of orbit and out of control. By detecting the waveform or any vibration in the antenna, it can be suppressed in the same way that noise is suppressed.

A piezoelectric device creates an electrical signal when it detects a vibration. It also will vibrate according to an electrical signal it receives. Putting piezoelectric devices on the antenna can result in vibrating the antenna in an opposite phase, thus eliminating the dangerous motion.

Use in apartments

One cool idea is to suppress unwanted noise from another apartment by vibrating your wall out of phase with the sound from next door.

For example, suppose the person in the next apartment has his stereo on real loud. In some cases, you can even feel the wall vibrate. By placing devices on the wall, you can detect the wall vibrations and generate vibrations in an opposite phase. Thus would completely cancel out the noise coming from the other apartment.

Although there are some new devices available that use your walls as a speaker by creating vibrations, it has not yet been combined with detectors and noise reduction electronics. This is an invention that is begging to be developed.

Summary

Active noise cancellation is a method to cancel out undesirable sound in real time. It is relatively easy to do with a single sound frequency, but it is much more difficult with complex sounds, such as the spoken word. Noise cancellation earphones are the most common devices. Other devices that do not require earphones are being developed.

SUMMARISING THIS , WHAT A LOAD OF WANK JUICE

Just because you could not understand any of it!

I couldn't understand any of it but the presentation was fantastic so I say what he says

[stoneyboy]

Although at times the speakers in my village are incredibly loud and annoying,they do in fact to me serve their purpose fairly well,only last year in mid september was i awoken by a loud blast at 3.30 am by the good ole chief telling me that our house was about to be flooded by four foot of flood water,very considerate of the old chap to let me know,luckily we didnt get flooded,but we did all sit in anticipation watching the small river at the back of the house edge its way up and over the top before it receeded,a truely memorable event aided only by the use of those village loud speakers,for i would not have woken up without them.

[canopy]

Although at times the speakers in my village are incredibly loud and annoying,they do in fact to me serve their purpose fairly well...telling me that our house was about to be flooded

That is shocking because on the contrary this demonstrates how terribly misused the system has become. Imagine if as some have suggested one had earplugs inserted so they could continue to sleep when such a message occurred? Imagine a person in a village who could not understand the message in Thai well enough to know they were in any danger. Imagine all those who have trained themselves to sleep through these things. Imagine the elderly who are hard of hearing. Imagine those just out of range enough from the speakers. Imagine if there happened to be a power failure that night. The possibilities of missing the message are endless. This speaker system should never be relied upon for an emergency. There are too many lives that it puts at risk.

[vincentc]

Up country, i got the same issue. it's the head monk, who had a tower with 3 speakers erected on the temple yard just across the street and is broadcasting all sorts of stuff nobody listens to. in an attempt to boost his money collecting business, he started reading the names of the donators together with the amount donated. all of that between 05:30 and 7 AM. Just after I finally managed to fall asleep despite dogs, cocks and the drunk driven motorbikes in the village.

To ridiculise this, I decided to put 1 single baht coin in the envelope (normal donations start from 100THB onwards) and put my name on it. I listened through the whole name listing for 30 minutes, and my name wasnt even mentioned! the fuc_ker!

i had a chat with the head monk whao asked me if i was into buddhism; i said i was, but after i saw his tower-preaching i realised they are nothing better than islam, who make noise more often but less long. He got the message, but since i am the only one who dares to complain, nothing happened.

The other villagers don't listen to his crap, but dare not to say it.

I now refer to the temple as Wat Siang Dang (noise temple) and Pra siang Dang (the noisy monk) and everyone things thats funny and some have adopted the naming.

I refused to have the wedding ceremony held by this monk. My in laws were afraid to 'loose face', but accepted at last to get the competition in. I told everyone in the village that it was because i hated the noise. all agreed and said the previous monk was better and he didnt do this.

Short circuiting has been one of my options, plan B would be to spray PU foam in the speakers themselves, but that would me requiring climbing the 10m high tower with my 70 kilograms on Thai country side engineered structures.

but then, since i am the only one daring to speak up and having both the balls and skills to do it, its gonna be too obvious that i am the culprit, especially since it will happen on just one of the few occasions that undersigned farang was spotted in town.

What about buying/leasing the land, break down the towers and plant some trees on it?

In the Capital, i ran away from my nice place in ramkhamhaeng because of the freakin Muslims spreading their opium to the people through loudspeakers; especially on fridays, there is a lengthy preach as part of the 'ceremony'.

I now fled to central Bangkok where the nights are - believe it or not - quieter than anywhere else. Enough people with common sense here not to allow any religious noise pollution.

[mstribling]

Great story about yourself. So you recommend moving?